20 - 26 October 2026: Post-Mortem
We experienced an issue with email notifications between 20 October and 26 October 2026. Our team has worked diligently to identify the root cause and implement a resolution. In this post-mortem, we want to share the details of what happened, why it happened, what we did to resolve it, and what we will do to prevent similar incidents in the future.
What happened?
During this period, some recipients did not receive email notifications from DRACOON. The issue mainly affected organisations whose incoming mail runs through certain corporate email security gateways. For these recipients, many notifications were rejected and not delivered. All other DRACOON functions were unaffected.
Why did this happen?
Before accepting a mail, some email security gateways check that the sender's domain is valid. A DNS service operated by a third-party provider began giving an incorrect answer for part of our notification sender domain's configuration. Because of that answer, these gateways wrongly treated our sender domain as invalid and rejected the notifications. Our own configuration and our mail delivery service were working correctly throughout.
What did we do?
After the first customer reports, we analyzed the delivery logs together with our email delivery partner and found that the rejections followed a clear pattern. We traced them to the third-party DNS issue. On 26 October, we changed the configuration of our notification sender domain so that it no longer depends on the affected third-party service. After the change, delivery returned to normal, and we monitored it closely to confirm the issue was resolved.
What can we do to improve?
We apologize for any inconvenience this incident may have caused. We are committed to ensuring the stability and reliability of our services and will continue to take proactive measures to prevent similar incidents from happening in the future.
If you have any questions or concerns, please don't hesitate to reach out to our support team for assistance.